Draughtproofing is a big one especially in old council houses like mine. I will be getting our windows done at some point but getting our roof replaced helped a lot (no loft as attic conversion) but even keeping doors closed can help trap that heat in.
I actually looked at the government schemes available to tenants. I dont think I qualify due to income but looked anyway.
First thing of interest is that new boilers are only offered if you dont already have central heating, so people with old inefficient boilers tough luck. Given my recent discovery 80% of my gas bill is there just so I can use gas, (not actual usage), this is more important than can be realised. Most important for low gas users.
Second thing was there is nothing for replacing windows, I know in my home, the draft pretty much all comes from my old wooden window frames. The windows are literally falling apart. When its windy outside (rare in my city, but was in march), the curtains will be away from the window with the draft lifting and pushing them away. Standing next to my front door you can feel it just standing there.
Wall insulation exterior/interior is offered, but surely this has much lower effect than fixing old drafty windows.
Loft insulation is offered, only relevant to people who have a loft.
Storage heaters with extended keep time are also offered. I assume only eligible if you already have storage heaters or are not suitable for central heating.
EDF offer a subsidised replacement boiler for their customers though.